YES YOUR FISH NEED IT! water conditioner removes the chlorine, chloramine and hard metals in your water that would otherwise be very harmful to your fish! Prime and Topfin are good cheap brands.

So what if your tanks are small, the water all comes from your taps. Tap water is not natural for fish and very dangerous to them! Other benefits is that most conditioners have a stress coat in them that replenishes the fish's natural slime coat when they're stressed.